A processing component configured to receive position sensor data from a first sensor attached to a shift rail of a transmission and determine from the first sensor data whether the shift rail is in a position of engagement of a first gear or a second gear or in a neutral position; receive position sensor data from a second sensor attached to the shift rail, determine from the second sensor data whether the shift rail is in a position of engagement of the first gear or the second gear or in the neutral position; compare the position determined from the first sensor data with the position determined from the second sensor data, and verify the shift rail position based on the comparison.
Further, a method for verifying shift rail position based on comparing data received from a first and a second sensor attached to the shift rail.
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11. A method, comprising:
receiving position sensor data from at least a first sensor proximate to a shift rail of a transmission, wherein the shift rails includes a first locator and a second locator positioned thereon, wherein the at least first sensor senses a change in a physical property resulting from an increasing distance between the first locator and the first sensor, and the at least first sensor senses the change in a physical property resulting from a decreasing distance between the second locator element and the at least first sensor; and
in a computing device, determining from the first sensor data whether the shift rail is in a position of engagement of a first gear, a position of engagement of a second gear, or in a neutral position.
1. A control module, comprising:
a processing component configured to:
receive position sensor data from at least a first sensor proximate to a shift rail of a transmission, wherein the shift rail includes two locator elements positioned thereon; and
determine from at least the first sensor data whether the shift rail is in a position of engagement of a first gear, a position of engagement of a second gear, or in a neutral position, based on a sensed change in a physical property resulting from an increasing distance between one of the two locator elements and the at least first sensor, and also based on the sensed change in a physical property resulting from a decreasing distance between the other of the two locator elements and the at least first sensor.
2. The control module of
receive position sensor data from a second sensor proximate to the shift rail;
determine the position of the shift rail from the second sensor based also on the distance of the second sensor from the two locator elements;
compare the position determined from the first sensor data with the position determined from the second sensor data; and
verify the shift rail position based on the comparison.
3. The control module of
4. The control module of
5. The control module of
6. The control module of
7. The control module of
8. The control module of
9. The control module of
wherein
the shift rail is one of a plurality of shift rails in a shift rail transmission;
the number of rails in the plurality of shift rails is equal to N;
one position sensor is attached to each shift rail; and
each sensor indicates whether the shift rail is in a position of engagement of the first gear, a position of engagement of the second gear, or in the neutral position, such that the N position sensors indicate three times N gear positions.
10. The control module of
12. The method of
receiving position sensor data from a second sensor proximate to the shift rail;
determining the position of the shift rail from the second sensor data based also on the distance of the second sensor from the two locator elements;
comparing the position determined from the first sensor data with the position determined from the second sensor data; and
verifying the shift rail position based on the comparison.
13. The method of
14. The method of
15. The method of
16. The method of
17. The method of
18. The method of
19. The method of
wherein
the shift rail is one of a plurality of shift rails in a shift rail transmission;
the number of rails in the plurality of shift rails is equal to N;
one position sensor is attached to each shift rail; and
each sensor indicates whether the shift rail is in a position of engagement of the first gear, a position of engagement of the second gear, or in the neutral position, such that the N position sensors indicate three times N gear positions.
20. The method of
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This application claims priority to U.S. Provisional Patent Application 61/231,134, filed Aug. 4, 2009, which is hereby incorporated by reference in its entirety. The following cases, entitled SHIFT RAIL TRANSMISSION POSITION SENSING WITH A MINIMUM NUMBER OF SENSORS, SHIFT RAIL TRANSMISSION POSITION SENSING WITH TOLERANCE FOR SENSOR LOSS, and SHIFT RAIL TRANSMISSION POSITION SENSING, of which the present case is one, have all been filed on the same date. The contents of the two applications that have a different title then the present application are hereby incorporated herein in their entirety.
In a transmission, it is desirable to have an indication of whether gears are fully engaged or disengaged. This information may be useful in either an open-loop or a closed-loop control system. In an open-loop transmission system, current gear position may be determined prior to commencing gear engagement. For example, in a shift rail transmission, the current position of each shift rail may be used to verify the appropriateness of translating one of the shift rails to a new position. Further, in an open loop shift rail transmission system, the duration of shift rail translation or travel from one position to another in response to a movement command of a specified duration may be used to update the command duration for subsequent shift rail movement. In a closed loop transmission system, gear or shift rail position may be used as feedback in the closed loop control so that, instead of asserting a movement command for a specified duration, the shift rail translates or travels until it reaches the desired position as indicated by the position sensor feedback.
A control system may include a system controller, further including a processor generating control signals and monitoring feedback signals. Multiple sensors may be employed to provide accurate position information, and the information from each sensor may be further used to cross-check the information from other sensors.
Accurate position information generally requires the use of several position sensors. However, in a system where cost, space, weight and the like may be constraining factors having too many sensors can be an issue. Therefore, it is desirable to minimize the number of sensors and the number of wires that must be run to the sensors potentially while still promoting redundancy in case one or more sensors fails.
In an exemplary control system, a processor may generate signals to control a movable element. The processor may also receive feedback from one or more position sensors to identify position of the movable element or to verify that the movable element is approaching or has reached an intended position. For example, the processor may compare position data from a sensor to an expected position, e.g., compare an expected time to an actual time between peaks of a received sensor signal; compare an expected value to a peak value of a received sensor signal; compare an expected value to the slope of a received sensor signal, etc. to identify position. In an open-loop control system, such comparisons may be used to adjust variables for the determination of a control command, e.g., if a longer-than expected time was required to reach a position, a software counter may be adjusted to increase the length of time that current is supplied to a solenoid, wherein the new counter value would be used the next time the solenoid is activated. In a closed-loop control system, comparisons of received signals to expected values may result in an error measurement between the sensed and expected positions, such that the processor generates further signals to further control the movable element to reduce the error in near real time. Such closed-loop control may be performed periodically or substantially continuously.
Comparison of a received signal value to an expected value may additionally provide diagnostic information for a sensor. For example, if the difference between a measured magnitude of the received signal versus an expected magnitude exceeds a predefined threshold, the processor may determine that the sensor signal is not valid, and may perform diagnostics to identify a failure mode of the sensor or its connections. Further, if it is determined that a sensor signal is not valid, the system may perform special steps to mitigate the impact of the loss of the sensor signal.
Selection and placement of the position sensors may result in a combination of sensor signals that contain not only position information for each sensor individually, but also position and diagnostic information determined from the combination of signals. For example, multiple sensors may be selected and placed so that the signals from the individual sensors are used to cross-check each other. The sensors may be similarly placed or may be offset, inverted or otherwise distinguishable from each other to provide better capability for cross-checking between the signals. Examples of cross-checking signals include determining a correlation between two or more signals and comparing to an expected threshold value; determining an average value for all of the signals and comparing to an expected envelope of values; and determining whether all of the signals indicate the same position. In the discussion that follows below the comparison takes place within a controller using a time domain although the same comparison may be done by the controller using a frequency domain. Moreover, under some approaches correlation may take place using distance rather than time or frequency. Alternative implementations are possible for checking and cross-checking signal information and what is described is only exemplary.
Using information from multiple sensors to allow for cross-checking between the sensors may allow for a reduction in the number of sensors, and a corresponding number of wires or other support elements (e.g., sensor fasteners) required in a system.
A control system may use multiple processors that read sensor signals and compare the values read between the processors to provide an additional layer of cross-checking.
System controller 120 includes a processing component 130, a control component 140 and a monitor component 150. System controller 120 may be implemented as hardware, firmware and/or software, and further may be implemented as any one or more computing systems and/or devices. For example, when system controller 120 is implemented as multiple computing devices, control component 140 and monitor component 150 may be co-located with the subsystem 110, whereas processing component 130 may be located remotely, e.g., as a separate hardware device, or a firmware or software component in a computing device. Co-location may include mounting of components directly on, adjacent to, within, etc., an element of subsystem 110. Remote in this context may include mounting of components in separate electronic modules, or separate physical locations, e.g. at a separate workstation or in a separate building. In one exemplary illustration, the entire system controller 120 may be integrated within the subsystem 110, e.g., as components on a circuit board mounted directly on or within a piece of equipment, such as electronics within a submersible pump.
As noted, processing component 130 may be implemented as one or more computing systems and/or devices. In general, computing systems/devices may employ any of a number of well known computer operating systems, including, but by no means limited to, known versions and/or varieties of the Microsoft Windows® operating system, the Unix operating system (e.g., the Solaris® operating system distributed by Sun Microsystems of Menlo Park, Calif.), the AIX UNIX operating system distributed by International Business Machines of Armonk, N.Y., and the Linux operating system. Examples of computing devices include, without limitation, a computer workstation, a server, a desktop, notebook, laptop, or handheld computer, or some other known computing system and/or device. Further, a computing device may be an embedded processor within an electronic module, and may further be an embedded processor within an integrated circuit.
Computing devices generally include computer-executable instructions, where the instructions may be executable by one or more computing devices such as those listed above. Computer-executable instructions may be compiled or interpreted from computer programs created using a variety of well known programming languages and/or technologies, including, without limitation, and either alone or in combination, Java™, C, C++, Visual Basic, Java Script, Perl, etc. In general, a processor (e.g., a microprocessor) receives instructions, e.g., from a memory, a computer-readable medium, etc., and executes these instructions, thereby performing one or more processes, including one or more of the processes described herein. Such instructions and other data may be stored and transmitted using a variety of known computer-readable media.
A computer-readable medium (also referred to as a processor-readable medium) includes any non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random access memory (DRAM), which typically constitutes a main memory. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, or any other medium from which a computer can read.
Controller 120 may control and monitor more than one subsystem 110. In one exemplary implementation controller 120 monitors and controls multiple vehicle subsystems. Not only may the controller 120 monitor and control the individual subsystems 110 such as vehicle subsystems, controller 120 may also monitor and control the larger system, such as a vehicle powertrain including transmission and engine components. To further explain, controller 120 may monitor and control multiple subsystems 110 while also monitoring and controlling system 100 at a higher level. Monitor and control at a higher level may provide more capability for identifying improper subsystem 110 behavior by observing the interaction between subsystems.
Control component 140 generally includes the appropriate interface for sending control signals to a particular subsystem 110. In one exemplary implementation, control component 140 is a circuit that converts electrical signals generated at the processing component 130 to electrical signals appropriate to activate a device in the subsystem 110. For example, control component 140 may include circuitry to convert one or more low-voltage digital signals to three high-voltage signals for driving a tri-phase motor, or a transceiver that converts digital signals from the processing component 130 to a serial data stream for control of a device using a serial protocol. In an exemplary system 100 in which control component 140 is co-located with subsystem 110, control component 140 may be, e.g., an electronic circuit attached to an actuator on a valve. In another implementation in which control component 140 is co-located with subsystem 110, control component 140 may receive information from remotely located processing component 130 in the form of a serial protocol, and convert the information to electrical signals, e.g., an analog voltage to apply to an electromechanical device driving a hydraulic piston. Control component 140 is adapted for the specific set of devices of subsystem 110 that are under the control of controller 120.
Monitor component 150 generally includes an appropriate interface for receiving input from the subsystem 110. In one exemplary implementation, monitor component 150 is a circuit that converts electrical signals received from subsystem 110 into electrical signals appropriate for processing component 130. For example, monitor component 150 may include circuitry to convert differential analog inputs into low voltage digital signals, or a transceiver to convert a two-wire serial protocol signal to a low voltage single line serial data stream. In an exemplary system 100 in which monitor component 150 is co-located with subsystem 110, monitor component 150 may be, for example, an electronic circuit attached to a sensor. In another illustrative implementation in which monitor component 150 is co-located with subsystem 110, monitor component 150 may receive information from subsystem 110 as, for instance, a tri-state digital signal, and transmit the information to remote processing component 130 using a serial protocol. Monitor component 150 is adapted for the specific set of information sources monitored by controller 120.
Interfaces 160 and 170 include one or more wired or wireless mechanisms for transmitting signals between system controller 120 and subsystem 110. For example, if communication between control component 140 and subsystem 110 is via a serial protocol, then interface 160 may include a cable meeting the specifications for the implemented serial protocol. As another example, if information from subsystem 110 is sent to monitor component 150 as analog signals then interface 170 may be wire of a gauge appropriate for the power requirements of the analog signal transmission.
Movable element 210 generally includes any device that based upon control signals or instructions changes location with one or more degrees of freedom. Movable element 210 may move constantly or infrequently, may move along one axis or have several degrees of rotational and linear freedom, may always return to its original location or may never return to its original location, etc. Movable element 210 may be propelled electrically such as through application of an electric field or magnetic field, or may be propelled mechanically.
Motion control of movable element 210 is accomplished by processing component 130 transmitting control commands via control component 140 and interface 160 to electromechanical interface 220, which in turn converts the commands into mechanical forces directed to relocating movable element 210. As discussed above, movable element 210 may be movable in a multitude of ways, including at various speeds, rotations, and directions. Therefore, electromechanical interface 220 may be implemented using a corresponding variety of approaches. A few examples of electromechanical interfaces are ones that convert electrical signals to hydraulic pressure, electrical signals to magnetic force, and electrical signals to spring tension. Notably, electromechanical interface 220 may convert electrical signals into more than one form of mechanical energy, e.g., for implementing “push-pull” control of a valve, or for implementing both lift and rotation of an object. Further, electromechanical interface 220 may convert electrical signals from control component 140 to electrical or magnetic fields as a propulsion mechanism for device 210, without conversion to mechanical energy. Electromechanical interface 220 may be implemented in multiple devices such as a mix of actuators and hydraulic devices, or in multiple stages such as first storing energy and then applying it to movable element 210.
One category of movable element 210 includes objects that move bi-directionally along an axial path. When closed-loop control of such an object is functioning properly, the object is mechanically shifted along a defined path to a desired point at a defined distance from the point of origination. The path of the object may be predefined mechanically, but may alternatively be defined dynamically. In either case, sensor 230 may be a position sensor that feeds back information regarding the position of the object to processing component 130 via monitor component 150. Thus, exemplary subsystem 110 may include a movable element 210, movable axially and bi-directionally, controlled by electromechanical interface 220, wherein the position of movable element 210 is sensed by one or more position sensors 230.
Sensor 230 generally includes a device for sensing a property of movable element 210. Generally, but not necessarily, sensor 230 is in the vicinity of or in close proximity to movable element 210. Examples of properties that sensor 230 may sense are position, temperature, humidity, speed, color, presence or absence, and pressure. Multiple sensors 230 may sense multiple properties. The information gathered by sensor(s) 230 is transmitted via interface 170 and monitor component 150 to processing component 130.
A locator 290 generally provides an indication of a known position, and may be implemented in a broad variety of ways. For example, locator 290 may be a divet or protrusion along a metal section, such that sensor 230 senses a change in a magnetic field caused by the inconsistency in the metal span at the divet or protrusion, or such that sensor 230 physically extends or retracts at the divet or protrusion, respectively. For another example, locator 290 may be a hole through a section of material, such that sensor 230 recognizes a change in received light between the reflections off of the bulk of the material and the illumination through the hole in the material. For a further example, locator 290 may be a magnet and sensor 230 may be a Hall effect sensor that senses a change in magnetic flux as it approaches or passes by locator 290. Other sensor 230/locator 290 pairs may utilize ultrasound, high frequencies, infrared light, radio waves, electric fields, hydraulic pressure, or any other mechanisms by which position may be determined.
Considerations for selection of locator 290 include environmental conditions, shape or movement or surface conditions of movable element 210, requirements of sensor 230, mechanical or electrical interference, etc. In some applications, multiple locators 290 and/or multiple sensors 230 are desirable. For such applications, the multiple locators 290 need not be the same or similar, and the multiple sensors 230 need not be the same or similar. It may actually be desirable to deliberately introduce differences in sensor 230 or locator 290 types and/or placement to introduce signal differences for purposes of cross-checking the signals, as discussed below.
Note that locator 290 may not be necessary. For example, sensor 230 may sense a difference in reflected light, electric field, magnetic field, etc. at a distal end of movable object 220 as it passes sensor 230. As such, locator 290 may be omitted in subsystems 110 in which identification of a distal end is an object.
A vehicle transmission control system is an example of a control system 100. Switching of gears in a vehicle is generally performed within a transmission. There are many possible transmission designs, some of which employ shift rails that move parallel to a gear axle or axles. Multiple gears are mounted on the gear axle(s). To engage two gears, an engagement element may be moved by a shift rail.
Proper gear engagement is critical to the proper functioning of a vehicle, and therefore it is desirable to verify appropriate gear position before or while engaging the gears. For a manual transmission in which the gear shift lever is mechanically linked to the gears, the verification may be performed at least partially by the driver by the position of the gear shift lever or by the sound or feel of the gear engagement at the beginning of a gear change. For an automatic transmission in which there is no mechanical link to the gears, the driver generally has no opportunity or capability to verify proper gear position except as indicated visually by the gear shift lever position, e.g., the PRNDL positions (Park, Reverse, Neutral, Drive, and Low.) Consequently transmission control, and especially automatic transmission control, is often implemented with significant redundancy, fall-back modes, diagnostics, and “sanity checks” or cross-checks of feedback from multiple subsystems.
Transmission control module (TCM) 320 includes a processing component 330, a control component 340, and a monitor component 350. The generalized function of these components was previously described with respect to system controller 120 components 130, 140 and 150, respectively. Processing component 330 is often implemented as multiple integrated circuits (ICs). For example, processing component 330 may represent two or more microcontroller ICs with associated memory ICs, and circuitry to monitor for proper functionality of all of the ICs. The function of processing component 330 includes gathering data from circuits internal or external to TCM 320, asserting commands to devices internal or external to TCM 320, providing open- or closed-loop control for various transmission subsystems, monitoring the status and condition of multiple circuits and ICs internal to TCM 320, and monitoring the status and condition of multiple devices external to TCM 320.
As an example of monitoring inputs, processing component 330 may monitor battery voltage, air temperature, atmospheric pressure, engine torque, speed, wheel slip, tire pressure, etc. to factor into the determination of appropriate gear engagement for the current conditions. As an example of asserting commands, processing component 130 may assert digital lines to one or more output drivers in control component 340, e.g., a field-effect transistor (FET) or the like, that causes the FET to provide current to an actuator in the transmission.
As an example of providing open-loop control, processing component 330 first verifies the positions of shift rails 360, and consequently the current status of gear engagement, by reading information from sensors 380 through monitor component 350, and then commands movement of one or more shift rails 360. As an example of providing closed-loop control, processing component 330 asserts a command to a FET, the FET provides current to an actuator in the transmission to move a shift rail 360, and processing component 330 receives feedback through monitor component 350 that shift rail 360 has moved to the desired position.
As an example of monitoring the status and condition of multiple ICs internal to TCM 320, processing component 330 may comprise a main microcontroller that performs monitor and control functions, a secondary microcontroller that performs a monitoring function including monitoring the functionality of the main microcontroller, and a watchdog microcontroller that monitors the operation of the secondary microcontroller. As an example of monitoring the status and condition of multiple devices external to TCM 320, processing component 330 may receive inputs through monitor component 350 from external devices in the form of serial or parallel protocol messages or in the form of digital or analog signals, and check that the various inputs are within expected ranges.
Control component 340 may include a wide variety of circuitry for implementing the desired transmission control. Control may be, e.g., through supplying current or voltage, or through a signal, as discussed above. In the exemplary implementation of system 300, control component 340 includes at least circuitry for executing the commands received from processing component 330. The circuitry depends on the actual design of the actuators in the transmission. If an actuator is “smart”, i.e., contains electronics, then control component 340 is conceptually divided between TCM 320 and the actuator. In such a case the portion of control component 340 physically located in TCM 320 may comprise a low current signal output. Note that although control component 340 is shown as controlling one actuator 370, control component 340 may additionally control many different external devices of many different types, and the external devices are not limited to the context of transmission 310 control.
Monitor component 350 may include a wide variety of circuitry for implementing the monitoring function. Monitoring may be, for example, through direct-wired interface to a sensor, direct-wired interface to another electronic module, or serial or parallel data link. The circuitry depends on the actual design of the signals being monitored. If a sensor is “smart”, then monitor component 350 is conceptually divided between TCM 320 and the sensor. In such a case, the portion of monitor component 350 physically located in TCM 320 may comprise a low current signal input. In the exemplary implementation of system 300, monitor component 350 is illustrated as receiving input from position sensors 380. However, monitor component 350 may additionally receive signals from many external devices of many types, and the external devices are not limited to the context of transmission 310 monitoring.
Actuators 370 may include any mechanical or electromechanical implementation for moving a shift rail 360. For example, an actuator 370 may be a solenoid that receives current from control component 340 and magnetically forces an armature to exert force on shift rail 360, or to exert force on an intermediate electrical, mechanical, hydraulic or other device that then exerts force on shift rail 360. Transmission solenoids include variable force and variable bleed solenoids.
There may be multiple position sensors 380 monitoring shift rail 360 to verify proper location during motion or at rest. Sensors 380 may be attached directly to shift rail 360, with one or more locators mounted elsewhere on transmission 310 or on the transmission 310 compartment. Alternatively, locators may be attached to shift rail 360 and sensors 380 attached to transmission 310 or on the transmission 310 compartment.
A shift-rail transmission generally has multiple shift rails 360, wherein each shift rail moves to engage one or two gears, and each shift rail 360 has one or more position sensors 380. There may be, e.g., one shift rail 360 for third gear and fifth gear, one for fourth gear and sixth gear, etc. It is highly desirable that the correct gear engage, and therefore processing component 330 may not only directly monitor position information of the shift rail, i.e. by evaluating individual sensor 380 information, but may also indirectly monitor position information, i.e. by using multiple sensor 380 readings and verifying that there are no inconsistencies in the data. An inconsistency may be apparent, e.g., if sensors 380 indicate that the transmission is in both reverse and fourth gear at the same time.
Also, as mentioned above, processing component 330 may determine that sensor 380 data is inconsistent with other types of data. For instance, one sensor 380 indicating that the transmission is in first gear may be inconsistent with vehicle speed information received from another electronic control module over a serial data link indicating that the vehicle is traveling at seventy miles per hour. As another example, processing component 330 may determine that sensor 380 data is inconsistent when transmission shaft speed as read through monitor component 150 indicates high revolutions per minute (RPM) but the sensor 380 typically associated with a gear corresponding to the high RPM indicates that the transmission is in neutral. Thus, more generally it may be desirable to compare sensor 380 data with a second source of position information that is within an expected range such as a range of vehicle speeds or transmission shaft speeds. It may further be desirable to perform additional cross-checking using other available information to determine whether an identified inconsistency actually indicates incorrect sensor 380 performance.
One example of using multiple sensors 380 to determine and cross-check shift rail 360 position is a shift rail 360 with two attached sensors 380 that respond to the presence of two locators to indicate reverse gear or forward gear engagement, or a neutral position therebetween. In one illustrative approach the locators may be magnets and sensors 380 may be Hall effect sensors that sense magnetic field. As the shift rail 360 moves, the two Hall effect sensors 380 sense the magnetic flux of their respective locators. As a Hall effect sensor 380 moves closer to a locator magnet, a current induced in sensor 380 increases. As a Hall effect sensor 380 moves away from a locator magnet, the current induced in sensor 380 decreases. In this example, the two sensors 380 will have different induced currents as they move toward or away from the two locator magnets due to their different placement. The current or measurement of current from the Hall effect sensors 380 is provided to transmission control module (TCM) 320. The use of magnets and Hall effect sensors in a shift rail system will be described in more detail below with respect to
An inconsistency in sensor 380 readings may indicate failure of one or more sensors 380 or failure of wiring to one or more sensors 380. It is therefore desirable to have the ability to detect a failure of the wiring or of one or more sensors 380. One detection means is to check for open circuits on the sensor 380 inputs to TCM 320. Open circuit detection for a set of sensors 380 is described below with respect to
Stepping back to the generalized subsystem 110, there are several possible sensor/locator configurations for sensing the position of a bi-directional axial movable element 210. The configurations of
Multiple sensors 230 may be used for redundancy or for cross-checking, or because the length of movable element 210 is too great for one sensor 230 to adequately sense the difference in position between sensor 230 and locator 290.
For all of the examples in
Sensors 230 need not be equidistant from locator 290 as shown in
For implementations using two sensors 230, if sensors 230 are the same type of sensor arranged on different sides of a locator, then there will be an inverse correlation in at least part of the information transmitted from the sensors 230. In addition to the usefulness of the information from each sensor 230, the inverse correlative information also may be desirable for cross-checking the sensors 230 against each other. For other implementations using two sensors 230, it may be desirable to use different types of sensors 230 to, e.g., eliminate or reduce errors due to design or manufacture of the sensors 230.
The changes sensed by sensor(s) 230 are translated into electrical signals for transmission to monitor component 150. In some exemplary systems 100, sensors 230 transmit information continuously to monitor component 150. In other exemplary systems 100, sensors 230 only transmit information when there is a change in the physical property being sensed.
Continuing with the example of the preceding paragraph, additionally or alternatively the 10-bit analog data values for multiple signals may be compared, and a result of the comparison further compared to an expected value. In this manner, processing component 130 may also determine whether a group of sensors 230 are performing acceptably. For example, if correlation between multiple signals is much lower than expected but the average signal strength of each of the signals is as expected, processing component 130 may indicate that there is an intermittent open circuit on a connection to one sensor 230 and that the sensor 230 and its connections should be checked. Thus, the processing component 330 may use the information from two sensors 230 to recognize an open circuit condition.
The x-y plots illustrated in
Also shown in
Using information from sensors 230 both individually and in a combinatorial fashion, e.g., peak-to-peak, peak-to-valley, differential, additive, correlative or other measurement, provides for cross-checking of the sensors, reducing the probability of error. Cross checking may also be used to identify processing errors.
Sensors 230 as described above with respect to
The configurations of
As discussed above, sensors 230 generally may be embodied in many different forms, and the output signals may be in many different forms. For example, sensors 230 may have analog or digital outputs, may transmit information serially, or may output signal strength information in a voltage or current pulse-width modulated (PWM) signal. Therefore, as also discussed previously, the signals plotted on the graphs of
The exemplary embodiments described above with respect to
The Hall effect sensors 730 and 740 may be selected to be opposite polarity from each other such that one outputs positive current for North to South magnetic fields and the other outputs negative current for North to South magnetic fields. With such a configuration, the peaks of the output current from the sensors 730 and 740 will have opposite phase in addition to offset. Offset plus phase inversion is illustrated in
An exemplary implementation using the sensor/locator configuration of
Returning now to the transmission example, shift rails 360 are moved back and forth to engage or disengage gears when shifting between gears or when shifting into neutral. Each shift rail may at least partially control gear engagement for two different gears. For example, a shift rail may control a gear engagement element that moves bi-directionally to engage different gears on either side of its travel path. In a dual-clutch shift-rail transmission, there may be multiple shift rails 360 that may be controlled to engage one gear while at the same time disengaging another, for smooth shifting and continuous torque. The processing component 330 determines the position of shift rails 360 to monitor the engagement of one gear concurrent with the disengagement of another during an upshift or downshift of the transmission 310. Movable element 210 may be one shift rail in either a single or dual clutch transmission that controls a gear engagement element for engaging reverse gear and first gear. Sensors 730 and 740 may be placed to distinguish between reverse gear engaged position, first gear engaged position, and both gears disengaged, i.e. neutral. Sensors 730 and 740 may output signals similar to those illustrated in
Continuing with the illustration of
In
While sensor 730 is between distance d5 and d6 from its point of origin, the strong signal from sensor 730 is consistent with first gear being engaged. The weakening signal from sensor 740 is also consistent with first gear being engaged because in the first gear engaged position, sensor 740 is far from magnets 710 and 720. Therefore, position information indicating first gear engagement is determined directly from sensor 730 and is cross-checked by considering the consistency of the information from both sensors 740 and 740.
Using another method to determine where the shift rail is at any time, the signal strengths of the sensors 730 and 740 are compared. For example, if sensor 740 signal is at a magnitude m1, from a look-up table it can be determined that there are two possible sensor 740 locations that will cause sensor 740 signal strength to be magnitude m1, as denoted on
Further, the use of two sensors such as sensors 730 and 740 in
In general, placement of sensors 230 and locators 290, plus selection of types of sensors 230 and locators 290, along with selection of monitor component 150 circuitry, allows for a broad variety of monitoring and cross-checking of a subsystem 110.
As discussed above, it is very important to know what position each shift rail 360 is in before and/or during moving the shift rail. Therefore, the position of each shift rail 360 as indicated by a sensor 230 is generally verified in some manner through a cross-check or sanity check, wherein a cross-check includes comparing actual position information, and sanity checking includes verifying that the position information is consistent with some other type of information such as a speed measurement. In the implementation illustrated in
A fifth sensor 230 is included in
Sensors 230 are read by at least one processor in TCM 320. Diagnostics may be performed on sensors 230 by TCM 320 in addition to the cross-checking and sanity checking discussed above. Diagnostics may include open circuit detection, short circuit to ground, short circuit to battery, over-current, and over-temperature. Open circuit detection is especially important due to the number of wires, splices, and connectors in the wire harness in a vehicle, as well as the physical stress on the wire harness and on the connections to the printed circuit board within TCM 320, any of which may become separated, detached or broken. Open circuit detection is discussed further below.
A primary processor 950 and a secondary processor 960 each may be, in addition to other functionality, programmed to perform one or more of reading sensors 230, cross-checking information from the sensors 230, and monitoring the other processor. For example, primary processor 950 may read a first sensor 230 on a shift rail for its functional information and read a second sensor 230 on the same rail for cross-check information, while the secondary processor 960 may read the second sensor 230 for its functional information and read the first sensor 230 for cross-check information. The primary processor 950 and secondary processor 960 may then share the corresponding position determination with each other.
Sensors 230 are illustrated in
Referring to
Connection 910b of sensor A is a reference for sensor A. For example, if sensor A outputs current proportional to pressure, there must be a source of current to sensor A. In such a case, current would be provided to sensor A through connection 910b. As another example, sensor A may output relative voltage on connection 910a, wherein the voltage on 910a is relative to the voltage at connection 910b.
Connection 910c of sensor A is a return wire for a 3-wire sensor 230, required for the 3-wire sensor to operate properly. The return wire may be, e.g., connected to a ground or a floating ground in controller 120. Generally but not necessarily, a 3-wire sensor 230 has better accuracy than a 2-wire sensor 230.
Connection 920 is illustrative of a common reference connected within the wire harness to each of the sensors A-E. Alternatively, each reference 91xb may be provided directly from controller 120, not shown.
Connections 930-936 represent electrical connection between different ones of the connections 91xb and connection 920 for a configuration with a common reference from controller 120.
Connections 91xc, the return wires for 3-wire sensors, may be connected to each other, and may also be connected to system controller 120 through connection 940. Alternatively, each return 91xc may be provided directly to controller 120, not shown.
When sensors 230 are connected as shown in system 900 with connections 930-936 and a common reference 920 to system controller 120, the electrical connections between the various wires may be through wire splices. For example, connection 936 may be spliced to connections 934 and 916b, connection 934 may be further spliced to connections 932 and 914b, connection 932 may in turn be further spliced to connections 930 and 912b, and connection 930 may be spliced to connection 910b and the common reference connection 938, which may be spliced to connection 920 from system controller 120. If any of the splices fail, one or more sensors 230 may no longer function properly. Table 1 below summarizes the results for open circuits on the various connections 930-936. As one example, if the splice of connection 934 to connections 932 and 914b fails, then sensors D and E will not function properly, and cannot be read by system controller 120. This situation is an open circuit of connection 934. The fourth column of Table 1 is titled “Open circuit connection 934,” and the entries corresponding to sensors D and E are “Cannot read D” and “Cannot read E,” respectively. The terms “Can read” and “Cannot read” refer only to whether or not the controller 120 is able to acquire valid data according to what the sensor 230 is sensing. The sensor 230 may still output a signal on connection 91xa if its reference connection 91xb is disconnected, but the signal will represent invalid data.
TABLE 1
Open circuits, impact on sensor readings
Open circuit
Open circuit on
Open circuit on
connection
Open circuit on
Sensor
connection 930
connection 932
934
connection 936
A
Can read A
Can read A
Can read A
Can read A
B
Cannot read B
Can read B
Can read B
Can read B
C
Cannot read C
Cannot read C
Can read C
Can read C
D
Cannot read D
Cannot read D
Cannot read
Can read D
D
E
Cannot read E
Cannot read E
Cannot read
Cannot read E
E
Table 1 may be used, e.g., when planning a wire harness design, to determine where to splice in sensors 230 for the most system 900 reliability.
Instead of splices, the common reference may comprise a common conductive surface to which the individual wires 91xb are attached. In this case, an open circuit condition on any of the connections 91xb results in loss only of the corresponding sensor 230.
The discussion above with respect to open circuits on connections 930, 932, 934, and 936 applies to both 2-wire and 3-wire sensor connections.
In similar fashion to the wire splices for the common reference, the connections 91xc of the common return for the 3-wire sensors may be spliced together in a wire harness, and if one of the splices becomes disconnected, one or more sensors may no longer function properly. Instead of splices, the common return may comprise a common conductive surface to which the individual wires 91xc are attached. In this case, an open circuit condition on any of the connections 91xc result in loss only of the corresponding sensor 230 reading.
For the configuration illustrated in
Alternative approaches to the illustration in
As discussed above, any number of shift rails 360, sensors 230, references and returns may be implemented within a transmission system. The concepts described above may be extended to cover the various possible approaches.
Therefore, more generally let N represents the number of position sensors 380 wherein each sensor is associated with one of N shift rails in shift rail transmission system 310. Each of the N shift rails 360 moves in one direction to engage a first gear and moves in another direction to engage a second gear, with a neutral position therebetween. Thus, the N shift rails 360 operate to engage two times N gears. Moreover, the two times N gears may be divided into subsets of gears such that the group of gears allocated to a subset is sufficient to enable operation of the transmission in select gears such as forward and reverse and over a predefined range of transmission shaft speeds.
Each sensor 380 is electrically coupled to a control module that provides an electrical reference to the sensor and receives data in the form of an electrical signal from the sensor. Moreover, the set of N sensors 380 may be divided into subsets and each subset is provided a common reference from the TCM 320. The processing component 330 of TCM 320 determines from data from each sensor 380 whether the shift rail 360 associated with that sensor is in a position of engagement of a first gear, a position of engagement of a second gear, or in a neutral position. When the two times N gears are subdivided into subsets of gears the sensors 380 may be similarly allocated into the same subsets. Therefore, if the common reference to one of the subsets of N sensors becomes unavailable, the associated subset of gears may be disabled.
To provide redundancy there may be a second source of position information for at least one of the shift rails 360. For example, the second source of position information for a rail may be a second position sensor on that rail. Another source of position information may be external information such as vehicle speed or transmission shaft speed as discussed above.
Having described how sensor information may be used to determine position information for a movable element 210 such as a shift rail 360, including a description of monitoring position sensors for shift rail transmission gear engagement, an exemplary implementation of a position monitoring process will be described.
In 1010, a processing component 130 first determines signals necessary for moving movable element 220 to a desired location. The necessary signals may be determined in part from the error signals between position indicated by sensors 230 and an expected position. The necessary signals are also determined, e.g., after receiving a request for a new location, or after determining a change in environmental variables such as temperature and pressure.
In 1020, processing component 130 sends the signals via control component 140 to electromechanical interface 220. For example, as discussed above, such a signal may include a command to a field effect transistor (FET) to provide current to an actuator in transmission system.
In 1030, electromechanical interface 220 converts the received signals to mechanical energy and causes movable element 210 to change position. For example, as discussed above, an electromechanical interface 220 may include an actuator that receives current from a FET in control component 140, wherein windings in the actuator generates a magnetic field in response to the current and forces a rod to move, which in turn directly or indirectly forces movable element 220 to a new position.
In 1040, position sensor(s) 230 indicates the position of movable element 210 to processing component 130 by transmitting signals to processing component 130 via monitor component 150. For example, as discussed above, a transmitted signal may include a serial data signal sent to monitor component 150, which converts the data to digital signals for receipt by processing component 130.
In 1050, processing component 130 interprets the signals from the sensor(s) 230. For example, as discussed above, such interpretation may include conversion of different types of data, received from different sensors 230 through monitor component 150, into normalized 10-bit analog data.
In 1060, processing component 130 compares the position information to information reflecting an expected position for movable element 210. For example, as discussed above, comparisons may include, but are not limited to: comparing the distance between peaks of a received sensor 230 signal to an expected difference between peaks; comparing an absolute value of a peak to an expected value of a peak; and comparing the sensor 230 signal over time to an envelope of the expected signal. Note that a combination of comparisons may be used also.
In 1070, if the position of movable element 210, as reported by sensor(s) 230, is acceptable based on the comparison of the reported position with the expected position, then process 400 ends. If, however, the position of movable element 210, as reported by sensor(s) 230 is unacceptable, then process 400 continues at 1080. For example, as discussed above, acceptability may include average signal strength exceeding a threshold, and signal strength remaining within an expected envelope.
In 1080, processing component 130 performs an optional diagnostics process or sub-process. The diagnostics process or sub-process may include further signal comparisons to identify which component in the system may be experiencing a failure. For example, if the average value of the signal from one sensor 230 is very low, it may indicate that the sensor 230 has an intermittent open circuit somewhere along the feedback path to processing component 130. Following 1080, process 1000 ends.
Process 1000 may also be executed in a loop, not shown, to provide for continuous position monitoring and control.
With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention.
Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation.
All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.
Reference in the specification to “one example,” “an example,” “one approach,” or “an application” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example. The phrase “in one example” in various places in the specification does not necessarily refer to the same example each time it appears.
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